[PHP] Fix #5338: InvalidArgumentException (#6685)

* Add endpoint definition which reproduces #5338 bug

* Update samples

* Add test case which reproduces #5338 bug

* Fix "InvalidArgumentException: Invalid resource type: object"

* Update samples

- ./bin/php-petstore.sh
- ./bin/security/php-petstore.sh

samples/client/petstore/php/SwaggerClient-php/docs/Api/FakeApi.md

@@ -11,6 +11,7 @@ Method | HTTP request | Description
 [**testClientModel**](FakeApi.md#testClientModel) | **PATCH** /fake | To test \"client\" model
 [**testEndpointParameters**](FakeApi.md#testEndpointParameters) | **POST** /fake | Fake endpoint for testing various parameters 假端點 偽のエンドポイント 가짜 엔드 포인트
 [**testEnumParameters**](FakeApi.md#testEnumParameters) | **GET** /fake | To test enum parameters
+[**testInlineAdditionalProperties**](FakeApi.md#testInlineAdditionalProperties) | **POST** /fake/inline-additionalProperties | test inline additionalProperties
 [**testJsonFormData**](FakeApi.md#testJsonFormData) | **GET** /fake/jsonFormData | test json serialization of form data
 
 
@@ -371,6 +372,50 @@ No authorization required
 
 [[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
 
+# **testInlineAdditionalProperties**
+> testInlineAdditionalProperties($param)
+
+test inline additionalProperties
+
+
+
+### Example
+```php
+<?php
+require_once(__DIR__ . '/vendor/autoload.php');
+
+$api_instance = new Swagger\Client\Api\FakeApi(new \Http\Adapter\Guzzle6\Client());
+$param = new \stdClass; // object | request body
+
+try {
+    $api_instance->testInlineAdditionalProperties($param);
+} catch (Exception $e) {
+    echo 'Exception when calling FakeApi->testInlineAdditionalProperties: ', $e->getMessage(), PHP_EOL;
+}
+?>
+```
+
+### Parameters
+
+Name | Type | Description  | Notes
+------------- | ------------- | ------------- | -------------
+ **param** | **object**| request body |
+
+### Return type
+
+void (empty response body)
+
+### Authorization
+
+No authorization required
+
+### HTTP request headers
+
+ - **Content-Type**: application/json
+ - **Accept**: Not defined
+
+[[Back to top]](#) [[Back to API list]](../../README.md#documentation-for-api-endpoints) [[Back to Model list]](../../README.md#documentation-for-models) [[Back to README]](../../README.md)
+
 # **testJsonFormData**
 > testJsonFormData($param, $param2)